Closure for steel drums



Sept. 8, 1965 w. M. ALLEN 3,208,624 I CLOSURE FOR STEEL DRUMS (SINGLE-THREAD CLOSURE) Filed Aug. 23, 1963 2 Sheets-Sheet 1 INVENTOR. lV/ZZ/fi M 4145 P 8, 1965 w. M. ALLEN 3,208,624

CLOSURE FOR STEEL DRUMS (SINGLE-THREAD CLOSURE) Filed Aug. 25, less 2 Sheets-Sheet 2 INVENTOR.

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Arr /PA/K$' United States Patent 3,2ti8,624 CLOSURE FOR STEEL DRUMS (SINGLE- THREAD CLOSURE) William M. Allen, Columbus, Ohio, assignor, by mesne assignments, to American Light Gage Drum Corporation, New York, N.Y., a corporation of New York Filed Aug. 23, 1963, Ser. No. 304,185 9 Claims. (Cl. 22(l-39) This invention relates to improvements in the closure construction for the openings in the walls of light weight, single-trip drum type shipping containers made of light gauge steel, where it is of particular importance that the weight and cost of the drum be kept to a minimum.

In the most commonly used closures for the openings in the head of ordinary or heavy gauge steel drums, the openings are provided with a surrounding upstanding flange, and some form of bushing or collar having internal threads is secured to the drum by the engagement of such flange with this bushing. The plug, having the usual external screw threads is screwed in place in the bushing, a suitable packing washer being included in order to insure a tight joint. In the light weight, single-trip steel drums, however, every practicable reduction in weight and cost, even of the closure, is important.

In order to simplify the closures for the openings in sheet metal containers it has heretofore been proposed to stamp a helix in the form of a single continuous thread at the container opening, but such a construction in a light gauge drum has been found to possess insufiicient strength.

Among the objects of the invention are the following: To produce a leak proof closure construction for light weight steel drums, especially of the 55 gallon standard size, at minimum cost, and which adds to the Weight of the drum only that of the closure member or plug, and at the same time provide a construction which will withstand the required rigorous tests to which such closures are customarily subjected-namely, such tests as the hydrostatic pressure tests, vacuum tests, the vibration tests, and the drop tests; to produce a closure construction wherein the part thereof which is on the container is made in one piece with the wall of the container; to produce a closure construction which can be formed by a single stamping operation by the use of standard plant equipment such as a punch press; to produce a closure construction which includes a closure member of the plug type having the usual flange, packing washer and con-- tinuous external threads, and which will also form a liquid tight joint with threaded pipe, pump connections, vent plugs, etc., utilized by the users of drum containers; to produce a closure construction which will afiord nearly complete drainage of the drum at final emptying; to produce a closure construction having the required strength to resist the necessary torque applied to the plug in tightening it; to produce a closure construction having the holding power to insure that the plug will not loosen during shipment, and having the stiffness required to resist deformation that might otherwise result in leakage.

In accordance with the present invention the material of the drum head itself provides the thread form which receives the threads of the closure plug. That is to say, the internally threaded portion of the closure construction is part of the drum itself. This eliminates the bushing referred to above. The container wall, such as the saddle area at the top of the drum, is formed with an embossment projecting outwardly and having a central circular opening therein. Surrounding this opening there are a plurality of serrations or teeth which are formed integrally with the embossment and which project angularly inwardly around the periphery of the opening and which are flexible and resilient. These serrations are ar- 3,298,624 Patented Sept. 28, 1965 ranged in the form of an inverted truncated cone and with the tips of the serrations located in a common plane. The serrations therefore are arranged in a single circular row.

The serrations are sufiiciently flexible so that the threads of a closure member or plug of a proper size can be forced into the serrated opening by axial movement alone and without rotation. That is to say, when applying the closure member to the serrated opening, instead of rotating the closure member in order to engage its threads with the threads on the drum, with the construction of the present invention, the plug is pushed into the opening, the flexible fingers being bent inwardly and passing over the successive threads of the plug until the packing washer stops the further advance of the plug, the fingers adjusting themselves to the thread helix of the plug. Then the plug is given a fractional turn, usually approximately a turn, in order to complete the assembly and clamp the packing washer so as to render the joint liquid tight.

This final tightening of the closure member causes the serrations or teeth to take a permanent set in the form of a helix corresponding to one complete turn of the thread on the plug. Consequently when the plug is removed the opening will be found to be provided with a single thread consisting of a helical row of serrations extending a full 360 around the opening in the embossment. If the container is not completely emptied the first time it is opened, the closure plug may be readily re-applied to the opening and into engagement with the single serrated helical thread.

It will be understood that if desired the circular row of serrations or teeth may be preformed in the shape of a helix corresponding to the thread on the plug, in which case the plug can be applied to the opening by rotation of the plug in the ordinary way, that is, by engaging the leading thread on the end of the plug with the preformed single helix of serrations. By thus preforming the single serrated thread the plug may be applied by hand and with the aid of a wrench. The plug may also be applied by axial movement as previously described, but it is desirable first to start the threads on the plug with the serrated thread before pushing or forcing the plug into position. As before, a fractional turn of the plug is required in order to set up the plug and make the joint tight.

However, even though the plug threads are not oriented with respect to the serrated thread, the plug may be forced axially into engagement with the preformed serrated thread and then turned approximately a turn to complete the assembly and provide a tight joint. The fingers will undergo a rebending to conform to the thread helix on the plug, and will be found to retain this helical shape after the plug is removed.

The serrated teeth are not applied to a circular opening in the flat wall of the drum container, but to a suitable embossment formed around the circular opening, as mentioned. Such embossment is circular in form and usually applied to a saddle portion of the drum. In this embossment the metal of the drum wall curves upwardly in a fairly large or generous radius of curvature. At the point where the upturned metal is substantially vertical, the metal surrounding the opening is bent in a reverse curve, and much more sharply than the upward curving of the metal just described. The serrations or teeth are made to project inwardly and downwardly from this reversed curvature of the embossment.

The shar bending of the metal forms a relatively narrow rim surrounding the serrations or teeth, which constitutes a circular rib that greatly strengthens the embossment and cooperates with the teeth or serrations to provide the required strength to Withstand the compressural stress in the teeth caused by the application of the plug, and particularly during the final turn-up of the plug to render the joint tight. The upper surface of such circular rib or crown of the embossment is flattened to provide a comparatively narrow annular area to receive the Washer on the closure plug.

The serrations or teeth are flexible, and bendto allow the insertion of the plug, but are arranged at such an angle to the plane of the embossment that they are wedged against the threads of the plug. As the plug tightens, the angle of the fingers is decreased and they exert radial pressure on the crown of the embossment. Thus the required pressure, between the usual gasket, lining the flange of the plug, and the annular surface on the crown 'of the embossment, is produced to render the joint leak proof.

The invention will be further described in connection with the accompanying drawings showing, by way of example, one embodiment of the closure construction.

In these drawings:

FIG. 1 is a side elevation, with the upper portion broken away and shown in section, of a light weight steel drum container having two of the improved closure constructions in the head thereof;

FIG. 2 is a fragmentary plan view of one of the closure constructions shown in FIG. 1, drawn to a greatly enlarged scale and with the closure member or plug removed, and thus illustrating only the closure opening and its internal thread device or arrangement;

FIG. 3 is a view in central vertical section taken on line 3-3 of FIG. 2 showing the portion of the closure construction which is a part of the drum container;

FIG. 4 shows a fragment of FIG. 3 drawn to a larger scale;

FIGS. 5, 6 and 7 are sectional Views similar to FIG. 3 showing the various steps of applying a closure member to the closure opening;

FIG. 5 shows the plug resting on the closure construction ready to be applied;

FIG. 6 shows the plug in position after it has been pushed into the closure opening;

FIG. 7 shows the plug after it has been turned up tight; and

FIG. 8 is a view similar to FIG. 3 showing the part of the closure construction which is on the drum after the plug has been removed (at the final emptying of the drum).

Referring to these drawings FIG. 1 shows a light gauge single-trip steel drum in which both the shell or cylindrical portion 16 and the two end portions, namely, the bottom 11 and head 12 are of 24 gauge sheet steel. One standard size of drum holds 55 gallons, and another 30 gallons. Bottom 11 and head 12 are secured to the opposite ends of the shell by means of chimes 13 which are of a construction that will withstand the various tests, mentioned previously, to which drums of this kind are required to be subjected. A chime construction which has been found to meet all these tests is set forth in application Serial No. 189,357, filed April 23, 1962, now Patent No. 3,160,312, granted December 8, 1964, and assigned to the same assignee as the present application. Shell is provided with a number of rolling hoops 14, usually 4, for the purpose of assisting in moving the drum about, and also to strengthen it.

In the head of the drum, for filling and emptying, there are customarily provided two openings 15 having removable closure members, usually in the form of plugs 16. As shown the two openings 15 are of the same size, but they are often made of different sizes. These openings are formed in saddle portions on diametrically opposite sides of the drum head close to the chime 13, and leaving a raised central portion 18.

In accordance with the present invention openings 15 are formed in one or more embossments 19 stamped in the metal of saddle 17. For a 55 gallon drum openings 15 are about 2%." in diameter and the height of embossment 19 is approximately The embossment starts from saddle 17 with a sweeping curve 20 (FIG. 4)

having a fairly generous radius of about and terminates upwardly in a crown 21 which has a narrow flat annular surface, to receive a packing or sealing washer and which is joined to the portion having the sweeping curve 29 by a sharply curved shoulder 22, the radius of which is only about Projecting inwardly and angularly with respect to the plane of the embossment and arranged radially around the inner rim of crown 21 are a plurality of serrations, teeth or fingers 23, advantageously 16 in number. Teeth 23, advantageously, are placed at an angle of approximately 30 to the plane of the embossment or the plane of the drum head. With the teeth at such an angle they produce a wedging action against the threads of the closure member at the final tightening thereof as will appear later on. The sharply formed crown or rib 21 of the embossment provides a comparatively rigid support for teeth 23.

The formation of embossment 19 and the fingers or teeth 23 is accomplished at a single stamping operation, so that all of these parts are formed simultaneously.

As may be seen in FIGS. 3 and 4 and also as shown in dotted lines in FIGS. 5 and 6 the tips 24 of fingers 23 are disposed in a common plane and also in a circle (FIG. 2). The diameter of this circle being approximately 2%" it will accommodate the threads 25 of a standard 2" diameter plug such as shown at 16 in FIGS. 57. That is to say, the tips 24 of fingers 23 lie in a circle which is slightly smaller than the diameter of the roots of the thread 25. Plug 16 is provided with the usual sealing washer 27 of any suitable material.

In applying plug 16 to the opening 15, to ready the drum for dispatch to the user, the plug is rested upon the surface of the serrations or teeth 23 as shown in FIG. 5. The plug is then pushed into the opening. The force required for this operation may be applied in any suitable manner as for example by means of the plunger 28 of an appropriate press.

As plunger 23 moves downwardly the lower end 29 of the plug will push or force the flexible teeth 23 to bend downwardly a suflicient amount to permit the passage of threads 25. The tips of fingers 23 will continue to pass over the several threads until washer 27 contacts crown 21 of embossment 13 thus stopping the further advance of plug 16 by the plunger.

Up to this point the plug has been inserted entirely by axial movement and without rotation. Rotation is now imparted to the plug to tighten it in the closure opening. This requires approximately a /4 turn of the plug by means of a wrench, or in any other convenient manner. The tips of the flexible fingers 23 arrange or adjust themselves to the thread helix, and as the tightening of the plug is completed sufficiently to clamp the washer 27 in place so as to form a liquid tight joint between flange 26 and crown 21 these teeth Will take on a permanent set, being arranged in one complete turn or thread helix as shown in dotted lines in FIG. 7 and in full lines in FIG. 8. FIGURE 8 shows the permanent arrangement of the teeth to form a single 360 serrated thread or helix after the plug 16 has been removed.

During the step of pushing the plug into the closure opening as shown in FIGS. 5 and 6 by plunger 28, the somewhat resilient teeth 23 flex or bend at first under the pressure of the lower end of the plug, and, later on, under the pressure of the threads themselves, as the several rows of threads pass the ends or tips of the ser rated fingers. However, when the plunger 28 is withdrawn and the plug 16 is turned up by the fractional turn so as to set up the plug tight, the upward pressure of the threads 25 against the ends of the teeth cause the teeth to swing upwardly to a slight extent, lessening somewhat the original angularity of the teeth with respect to the plane of the embossment 19 and producing a wedging action against the plug. This wedging action of the teeth produces considerable upward pressure against the crown 21 of the embossment.

The circular rib formation of the crown, however, serves to strengthen the teeth 23 and to enable a single row of these serrations formed in the sheet metal of saddle 17, that is, the metal of the drum, to withstand the necessary clamping pressure on washer 27, between crown 21 and the flange of plug 16, to produce a tight joint. Moreover the closure construction will Withstand the various tests which are required by the Interstate Commerce Commission for closure for steel drum containers.

Although it is advantageous to apply the closure plug to the serrated teeth 23 while they are arranged in circular form as shown for example in FIG. 3, the serrated fingers may be preformed into a thread helix as shown in FIG. 8 if desired. That is to say, the fingers 23 may be given the form of a thread helix before the plug is applied to the closure opening. In that event it is desirable, in applying the plug, to start the threads 25 on the plug at the entrance 30 (FIG. 8) of the single helical thread. By thus orienting the plug it will rest in horizontal position on the embossment. It may then be forced into the opening by means of plunger 28 and then given the final fractional rotation to tighten washer 27 and produce a tight joint, or the closure plug may be applied entirely by rotation in the ordinary manner of screwing a plug into a threaded opening.

It has been mentioned that the provision of the serrated teeth permits more complete drainage of the drum than is possible with closure constructions of the ordinary type. When the drum is turned upside down at the final emptying substantially all of the liquid will drain out either over the edges of teeth 23 or through the notches 31 (FIG. 3) between the teeth.

I claim:

1. In a closure construction for light gauge steel drum containers, a container wall formed with an embossment projecting outwardly therefrom, the embossment having a circular opening therein, a plurality of flexible serrations integral with the embossment and projecting angularly inwardly around the periphery of the opening, these serrations being sufficiently flexible to permit a threaded closure plug to be applied to the opening by axial movement without rotation, the threads on the plug causing the serrations to bend to allow the threads to pass them during such axial movement.

2. A closure construction as claimed in claim 1 in which the embossment includes a circular portion projecting outwardly from the container wall and having a smooth convex curvature outwardly from the surface of the wall, said embossment also having a sharp reverse curvature at its outer portion forming a circular shoulder adjacent the bases of the serrations.

3. A closure construction as claimed in claim 1 wherein the serrations are preformed in the shape of a thread helix corresponding to the threads of a cooperating closure member.

4. A closure construction as claimed in claim 1 wherein the serrations are disposed at an angle of approximately 30 to the plane of the embossment.

5. In a closure construction for light gauge steel drum containers, a container wall formed with a circular opening therein including an embossment projecting outwardly from the wall and surrounding the opening, a plurality of serrations integral with the embossment and projecting angularly inwardly around the periphery of the opening, and a closure plug having a flange and sealing washer and having continuous external threads for engaging the serrations, the serrations being sufliciently flexible to permit the closure plug to be applied to the opening by axial movement without rotation, the threads on the plug causing the serrations to bend to allow the threads to pass them until the flange presses the Washer against the embossment.

6. A closure construction as claimed in claim 5 wherein the embossment is provided with a narrow flat annular upper surface for engagement with the sealing washer.

7. In a closure construction for light gauge steel drum containers, a container wall having a circular opening therein and having a plurality of integral serrations disposed around the periphery of the opening and projecting angularly inwardly thereof, these serrations being sufliciently flexible to permit a threaded closure plug to be applied to the opening by axial movement without rotation, the threads on the plug causing the serrations to bend to allow the threads to pass them during such axial movement, the plug being given a final fractional rotative movement to effect the tightening of the closure, and the container wall having a circular shoulder formed therein adjacent the serrations to withstand the outward pressure of the serrations when the closure member is given such final rotative movement.

8. A closure construction as claimed in claim 7 wherein the serrations are disposed at an angle of approximately 30 to the plane of the embossment.

9. In a closure construction for light gauge steel drum containers, a container wall formed with a circular opening therein including an embossment projecting outwardly from the wall and surrounding the opening, a plurality of serrations integral with the embossment and projecting angularly inwardly around the periphery of the opening, and a closure plug having a flange and sealing washer and having continuous external threads for engaging the serrations, the serrations being sufliciently flexible to permit the closure plug to be applied to the opening by axial movement without rotation, the threads on the plug causing the serrations to bend to allow the threads to pass them until the flange presses the washer against the embossment, and the plug being given a final fractional rotative movement to effect the tightening of the closure, such final movement causing the serrations to take a permanent set in the form of a thread helix.

References Cited by the Examiner UNITED STATES PATENTS 1,915,300 6/33 Draper 220-39 2,156,540 5/39 Melrath 22039 THERON E. CONDON, Primary Examiner.

GEORGE O. RALSTON, Examiner. 

1. IN A CLOSURE CONSTRUCTION FOR LIGHT GAUGE STEEL DRUM CONTAINERS, A CONTAINER WALL FORMED WITH AN EMBOSSMENT PROJECTING OUTWARDLY THEREFROM, THE EMBOSSMENT HAVING A CIRCULAR OPENING THEREIN, A PLURALITY OF FLEXIBLE SERRATIONS INTEGRAL WITH THE EMBOSSMENT AND PROJECTING ANGULARLY INWARDLY AROUND THE PERIPHERY OF THE OPENING, THESE SERRATIONS BEING SUFFICIENTLY FLEXIBLE TO PERMIT A THEREADED CLOUSE PLUG TO BE APPLIED TO THE OPENING BY AXIAL MOVEMENT WITHOUT ROTATION, THE THREADS ON THE PLUG CAUSING THE SERRATIONS TO BEND TO ALLOW THE THREADS ON THE PLUG CAUSING THE ING SUCH AXIAL MOVEMENT. 